title: Decarboxylase gene expression and cadaverine and putrescine production by Serratia proteamaculans in vitro and in beef.
abstract: Studies of the molecular basis of microbial metabolic activities that are important for the changes in food quality are valuable in order to help in understanding the behavior of spoiling bacteria in food. The growth of a psychrotrophic Serratia proteamaculans strain was monitored in vitro and in artificially inoculated raw beef. Two growth temperatures (25°C and 4°C) were tested in vitro, while growth at 15°C and 4°C was monitored in beef. During growth, the expression of inducible lysine and ornithine-decarboxylase genes was evaluated by quantitative reverse transcription-PCR (qRT-PCR), while the presence of cadaverine and putrescine was quantified by LC-ESI-MS/MS. The expression of the decarboxylase genes, and the consequent production of cadaverine and putrescine were shown to be influenced by the temperature, as well as by the complexity of the growth medium. Generally, the maximum gene expression and amine production took place during the exponential and early stationary phase, respectively. In addition, lower temperatures caused slower growth and gene downregulation. Higher amounts of cadaverine compared to putrescine were found during growth in beef with the highest concentrations corresponding to microbial loads of ca. 9CFU/g. The differences found in gene expression evaluated in vitro and in beef suggested that such activities are more reliably investigated in situ in specific food matrices.
authors.affiliation: Department of Agricultural and Food Sciences, University of Naples Federico II, Via Università 100, 80055 Portici, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: De Filippis
authors.forename: Carmela
authors.initials: C
authors.lastname: Pennacchia
authors.forename: Rosangela
authors.initials: R
authors.lastname: Di Pasqua
authors.forename: Alberto
authors.initials: A
authors.lastname: Fiore
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Fogliano
authors.forename: Francesco
authors.initials: F
authors.lastname: Villani
authors.forename: Danilo
authors.initials: D
authors.lastname: Ercolini
mesh_terms: D000818:Animals; D002103:Cadaverine / Q000032:analysis / Q000096:biosynthesis*; D002262:Carboxy-Lyases / Q000235:genetics* / Q000378:metabolism; D002417:Cattle; D005516:Food Microbiology; D015964:Gene Expression Regulation, Bacterial; D008460:Meat / Q000032:analysis / Q000382:microbiology*; D009955:Ornithine Decarboxylase / Q000235:genetics* / Q000378:metabolism; D011700:Putrescine / Q000032:analysis / Q000096:biosynthesis*; D012705:Serratia / Q000201:enzymology / Q000235:genetics; D053719:Tandem Mass Spectrometry; D013696:Temperature
chemical_list: D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase; C021520:lysine decarboxylase; D002103:Cadaverine; D011700:Putrescine
keywords: Biogenic amines production; Cadaverine; Decarboxylase genes; Meat spoilage; Putrescine; Serratia proteamaculans